A little old couple walked slowly into McDonald's one cold winter evening. They were so old that they looked out of place among the young families and young couples eating there that night.

    Some of the customers looked admiringly at them. You could tell what the admirers were thinking. “Look, there is a couple who has been through a lot together, probably for 60 years or more!”

    The little old man walked right up to the cash register (收银台), placed his order with no hesitation and then paid for their meal. The couple took a table near the back wall and started taking food off the tray (托盘). There was one hamburger, one order of French fries and one drink. The little old man unwrapped the plain hamburger and carefully cut it in half. He placed one half in front of his wife. Then he carefully counted out the French fries, divided them in two piles and neatly placed one pile in front of his wife. He took a sip of the drink, his wife took a sip and then set the cup down between them.

    As the man began to eat his few bites of hamburger the crowd began to get restless. Again you could tell what they were thinking, “That poor old couple. All they can afford is one meal for the two of them.”

    As the man began to eat his French fries one young man stood and came over to the old couple's table. He politely offered to buy another meal for the old couple to eat. The old man replied that they were just fine. They were used to sharing everything.

    Then the crowd noticed that the little old lady hadn't eaten a bite. She just sat there watching her husband eat and occasionally taking turns sipping the drink.

    Again the young man came over and begged them to let him buy them something to eat. This time the lady explained that, no, they were used to sharing everything together.

    As the little old man finished eating and was wiping his face neatly with a napkin the young man could stand it no longer. Again he came over to their table and offered to buy some food.

    After being politely refused again, he finally asked a question of the little old lady. “Ma'am, why aren't you eating? You said that you share everything. What is it that you are waiting for?”

    She answered, “The teeth”.

    Energy goes from one plant or animal to another. A food chain shows how this energy moves. Each time an animal gets eaten, its energy is passed onto the animal that eats it. The food chain is very important because it keeps the balance of nature. If one part of the food chain disappears, it can affect all the other plants and animals. Any threat to the food chain is a threat to the environment's biodiversit(生物多样性). The food chain helps keep animal populations in balance. However, if something happens to increase or decrease one of the links in the food chain, that balance is broken. If one animal becomes endangered, it puts all the animals above it at risk.

    Some of the threats are natural, such as wildfires, hurricanes, tornados, floods and so on. But the biggest threats to the food chain come from you and me. These threats include overhunting, overfishing, logging, farming, development, pollution, etc. The food chain is endangered anywhere humans have had an effect on the natural environment.

    A recent study shows that the overfishing of large sharks is damaging the food chain along the US Atlantic coast. Canadian and American scientists say sharks are being killed in great numbers for their meat and fins(鳍). Now, not enough sharks are around to eat the cownose(牛鼻) ray. The ray's population has increased and they have eaten up the shellfish to the point where it has hurt commercial(商业的) fishing.

    Many of us disturb the natural environment in our own backyards. It's up to us to take care of the environment and try not to disrupt the natural food chain. If we don't act responsibly, animals will start disappearing.

    There is no doubt e-commerce is growing, and it will continue to grow. However, physical stores would not die as a result of the rise of e-commerce, at least not in the near future. The idea that e-commerce is taking over physical stores has already misguided many people. Physical stores are far from vanishing (消逝), and there are some solid reasons for it.

    The projections for online spending is optimistic with 150 billion expected to be spent in the coming three years, yet we are also expecting 300 billion in spending at physical stores in the same duration. Do you still think that physical-store shopping is too small to sustain (支撑) the e-commerce blow?

    Even though consumers are staying away from physical stores that follow older concepts, yet we are seeing the rise of fresh concept stores all around the US. We are seeing innovative and attractive success stories of physical stores, ranging from clothes stores to restaurants to health spas. It would be easy to assume that this trend will continue.

    Indeed, many shopping malls are dying, yet there are still some shopping centers that are performing well. You can see this for yourself by visiting shopping malls near you. What I want to emphasize here is that not all shopping centers are made equal, just like not all e-commerce retailers (零售商) are made equal. Both shopping malls and e-commerce sites can lose business if they fail to maintain productivity through improvements and innovations. When you visit shopping centers that are serious about their business, you would see their shops and parking lots packed.

    On the other hand, even e-tailers like Amazon have experimented with pop-up shopping concepts. It is important to bear in mind that consumers prefer face-to-face interactions instead of online interactions during shopping, meaning that physical stores are going to stay there.

    Still, e-commerce retailers are seeing all of their excitement disappear as they settle the sales tax problem associated with e-tailing. As of now, five states of America have already imposed sales tax on purchases through e-commerce sites, and e-tailers in those states have already witnessed 6 to 12 percent decrease in sales.

    This reinforces the fact that physical stores are here to stay, and if you are still undervaluing their growth, you are omitting (省略) a huge chunk of the retail representation.

    I'm a reporter. Last month I was in Stockholm, Sweden. Now I'm in Frankfurt, Germany. Next month, who knows?

    You certainly won't believe that I can call you from my laptop, which is what I'm often doing these days using something called Skype.

    Skype lets me call any phone number anywhere in the world for about 2 cents a minute, a little more to some places, such as the Middle East and Asia. My computer does the dialing, and the processing of incoming and outgoing voices. All you need is a broadband connection (宽带接头). With the basic version of Skype, all anyone needs to make or receive a call is to install the program on his or her computer (and that includes personal digital assistants). All calls from PC to PC are free.

    You don't even need a pair of headphones, though headphones can be a good idea if you wish to be discreet. I use my laptop's built-in microphone.

    The paid service for calling regular telephones is called SkypeOut. The quality is completely clear, provided that there's not too much traffic on the Internet. If there's an echo, hang up and try again, and it usually gets better. There is one warning: on some computers, especially those running older versions of Windows, it doesn't always work, or can sound like a confusing conversation. You can't hear a thing.

    Skype was invented chiefly by a Swede named Niklas Zennstrom along with a group of programmers in Estonia.

    It's nothing unusual for people to multitask nowadays. But the ability to do a number of things at the same time could be different between the two sexes.

    A team of UK researchers recently compared the performances of 120 women and 120 men in a computer test about switching(转换) between tasks of counting and shape recognition.

    Men equalled women when tasks were done one at a time. But when the tasks were mixed up, there was a clear difference. According to the paper published in the journal BMC Psychology, both women and men slowed down and made more mistakes as the switching became more rapid. But men were slower, taking 77 percent longer to answer, while women took 69 percent longer.

    To make the experiment more connected to day-to-day life, researchers tried a second test. A group of women and men were given eight minutes to complete a series of everyday tasks, such as finding restaurants on a map, doing simple math problems, answering a phone call, or deciding how they would search for a lost key in a field.

    Once again, women performed better than men in the test, especially in the key-searching task.

    Where do women get the ability to keep organized under pressure better than men? Researchers believe that it has its origins in evolution(进化). In ancient times, women had to keep an eye on children while cooking meals. Meanwhile, men only needed to focus on hunting.

    However, as with all studies, the results don't necessarily apply to every single person in the world. "We don't mean that men can't multitask, or that only women can," researcher Keith Laws of the University of Hertfordshire, UK, told BBC News. "We are saying that the average woman is better able to organize her time and switch between tasks than the average man."